Make Resulting Bencodex data from BuildAction compatible with other @planetarium libraries

[Akamig]

Curerntly BuildAction is returning bencodex data in Uint8Array, but @planetarium/tx is recieving unencoded bencodex value.

So put it simply,

• We generate action with constructed JS Object as plainValue
• We get serialized bencodex dictionary in Uint8Array
• We need to Deserialize it before put it in @planetarium/tx, requiring unnecessary bencodex import.

So I think we should decide whether action builder output serialized Uint8Array or BencodexDictionary. However, we're working with C# interop, passing BencodexDictionary as output can possibly be hard.